field



(No Model.) 3 Sheets-Sheet 1.

s. D. FIELD. DYNAMO MULTIPLE TELEGRAPH.

No. 288,786. Patented Nov'. 20, 1888.

I JJVVEWTCR W21)? M By M vfl ttorneys Stepken D'Field! t e e h S S t e eh S 3. D L E T1 F D S H e d o .M o m DYNAMO MULTIPLE TELEGRAPH.

No. 288,786. Patented Nov. 20", 1883.

By his .[lttrmneys IV'ITN'ESSES' directions, simultaneously.

.connections.

NITED- STATES .ATENT rricE.

DYNANIO MULTIPLE TELEGRAPH.

SPECIFICATION forming part of Letters Patent No. 288,786, dated November20, 1883.

Application filed August 29, 188i.

To all whom it may concern.-

Be it known that I, STEPHEN D. FIELD, a citizen of the United States,and a resident in the city, county, and State of New York, have inventedcertain new and useful Improvements in the Method of and Apparatus forMultiple Telegraphy, of which the following is a specification.

My invention relates to the construction and organization of apparatusemployed for transmitting several communications telegraphicallyover asingle conductor, in either or both Heretofore it has been customary, inorganizing apparatus for multiple telegraphy, to provide at each stationtransmitting-keys for sending to the main line currents of differentchar acters, the character of each current being dependent upon theparticular key, or combination of keys, which may at any time beemployed, and to so include in the circuit of the main linereceivinginstruments adapted to respond to the currents coming from thedistant station, that each cur-rent having traversed an y or all oftheinstruments will reach the earth by way of the transmitting-keys andthe battery- To insure the successful operation of the receiwing-instruments in response to their respective currents, it isessential that the comparative resistances of the different branchcircuits, which the incoming currents are compelled at diiferent timesto traverse, be accurately adjusted or equated, and that the balance ofthe line be at all times correctly maintained. Owing to the severalfacts that the path by which an incoming current reaches the earthchanges in accordance with the relative positions of the respectivekeysat the receivingstation, that more or less batterypower andconsequent resistance is included in the earth-circuit according tothese positions, and that the contact-points of the keys forming aportion of the earth-circuit at any given moment offer more or lessresistance according as they chance to form poor or good connections, itis found exceedingly difficult to maintain the balance of the line withsuffi- 'cient accuracy to render such systems practically successful.

The object of my invention is to provide means for sending to the line.currents or im- (Xo model.)

pulses of any required character, and at the same time to provide forthe incoming currents a ground-connection of constant resistance,whereby currents from the receiving-instruments may reach the earthindependently of the transmitting devices.

My invention consists in placing an armature adapted to be rotated atany required velocity within the field of force of one or more solenoidselectricallyindependent thereof, but capable of being traversed bycurrents, impulses, or undulations of electricity of determinatestrength and polarity, thereby creatin g a field of magnetic forcethrough or within which the armature moves. Corresponding currents,impulses, or undulations will thereby be generated in the coils of thearmature, which currents are transmitted to the line by means ofsuitable commutators.

It also consists in combining with the transmitting apparatus suitablereceiving-instruments adapted to respond, respectively, to differentclasses of currents transmitted from the opposite terminal of the line,and in providing an electrical connection between the receiving-instruments and the earth by way of the com mutators of thearmature, one of which is arranged to receive currents of one polarityand is connected with the line-wire, while the other is arranged forreceiving currents of the opposite polarity and is connected with theearth.

There are several methods of applying my invention to multiple teleg"aphy, all dependout, however, upon the same general principle ofgenerating the currents to be transmitted uponthe main line in the coilsof an armature in response to and in correspondence with the field offorce created by the trans-.' mission of electric currents throughsolenoids located in the vicinity of the armature, and of providing forthe incoming currents an earthconnection which is independent of thetransmitting devices and circuits.

Of the accompanying drawings, illustrating the general method ofcarrying out'my inven tion, Figure 1 is a diagram showing itsapplication to seXtupleX telegraphy, and Figs. 2 and 3 to two differentsystems of quadrnplex telegraphy.

. Referring to Fig. 1, L represents a main line rhythmical pulsations.

uniting two telegraphic stations, which, for convenience, will behereinafter termed stationI and station II. At station I, Ihave shownthree independent keys or transmitting devices, two of which are adaptedto send currents of determinate strength and polarity throughcorresponding local circuits, constituting solenoids about a rotatingarmature. The remaining key acts to produce rhythmical electricalpulsations or variations in its local circuit or solenoid. At stationII, I have shown three receiving-instruments adapted to respond,respectively, to currents of a given strength without reference to theirp0- larity, currents of a given polarity, and

The method of transmitting the currents or impulses of the severalclasses will be more particularly described with reference to theconstruction of the apparatus itself. The receiving apparatus R atstation I, I have indicated merely, deeming it unnecessary to illustrateit in full, as it is in effect the same as that shown at station II.

Considering first the transmitting apparatus, A represents an armaturehaving the same general characteristics as the armatures commonlyemployed in dynamo-electric generators. In this instance it is one ofthe type known as the Gramme ring, and consisting of coils of insulatedwire a,-wound upon a soft-iron ring, a, in a manner well understood.constructed to be rotated by means of suitable motor power andconnections. (Not shown.)

Two commutator-brushesorsystems of brushes, 1 Y b and b, rest againstthe surface of the commutator B, which is of the usual construction Thebrushes 1; and b are so arranged with reference a to. thecommutator-sections that cur-rents off one polarity generated within thecoils of the armature will be received upon the brush b 1 andtransmitted to the line L,with which it is connected, while currents ofthe opposite polarity will be received upon the brush 1) and Gontrary tothe method adopted in dynamo-elecf tric machines, however, no portion ofthe currents generated in the coils of the armature is employed forintensifying the field of mag- 1 and revolves with the armature A.

reach the earth at E through the wire I.

netic force; but the latter is entirely dependent upon the passage ofcurrents from three:

local batteries, 0 0 0, through the coils of wire constituting threesolenoids, c o a", re-

. spectively included in the circuits of the three batteries, andenveloping three sections of the armature, but electrically independentthereof.

The batteries 0 and 0* are of different electromotive forces, thebattery 0 having preferably about one-half as many .cells as the battery0 and they are so included in their respective circuits that currents ofopposite polarities may be caused to traverse the correspondingsolenoids, c and 0 in the same or corresponding directions by closingtheir respective transmitting-keys K and K Thus, when It is rived from abattery having an electro-motive force of, say, ten volts will traversethe solenoid c in the direction indicated by the arrow, and when the keyK is closed a negative current, derived from an electro-motive force oftwenty volts, will traverse the solenoid c in the same direction. Theeffect of the transmission of such currents will be to cause currents ofproportionate strength to be generated in the coils of the armature A,if it be revolved through or within the magnetic field thus created.When the key K alone is closed, a series of impulses of alternatingpolarity will be generated in the coils at, having a strength dependentupon the field of force occasioned by the passage of the current fromthe bat- .tery 0 through the solenoid c, and these impulses will becollected with respect to their polarity by the commutator-brushes b andb in a manner well understood. A continuous current or impulse of agiven polarity say positivewill thus be transmitted over the line L fromthe brush 7), the duration of which will depend upon the duration of thecurrent traversing the solenoid. For convenience, this resultant currentwill be hereinafter referred to as due to an electro-motive force of tenvolts. \Vhen the key K alone is depressed, a current or impulse of astrength dependent upon the field of force created by the flow of acurrent from the battery 0 through the solenoid a, but having theopposite polarity from that occasioned by closing the key K, will betransmitted to the line. This current may be considered as a negativecurrent due to an electro-motive force of twenty volts. NVhen both keysare simultaneously closed, the current sent to line will have a strengthproportionate to the field of force occasioned by the combined-effectsof the batteries 0 and o that is to say, the current caused to traversethe main line will be a negative current due to an electro-motive forceof ten volts. The current thus transmitted may be considered a negativecurrent. In this manner currents of three different strengths may betransmitted upon the main line through the instrumentality of the keys Kand K and these currents may be employed for actuating two differentreceiving-instruments at station II, in a manner hereinafter minaterate, depending upon its construction.

It is provided with a contact-spring, g, which is included, togetherwith the electro-magnet F, in the circuit of the battery 0, which bat-'sioned bythe depression of the keys K, K,

tery is preferably of comparatively small electro motive force-forexample, three volts. This instrument constitutes an automaticinterrupter, and when the circuit of the battery 0' is closed by thedepression of the transmitting-key K the reedarmature will be throwninto vibration, the rate of which will depend upon the pitch or note towhich it is tuned. So long as the key K remains depressed, thisvibration will continue and the circuit of the battery 0 will be brokenat each vibration, thus establishing in the solenoid c an intermittentor pulsatory current, the polarity and direction of which are preferablythe same as those of the current caused by the depression of the key Kto traverse the solenoid 0 The current generated in the coils a of thearmature A, in response to the pulsatory currents in the solenoid a,will, it is evident, itself be pulsatory, and this current will be sentto line in the same manner as alreadydescribed with reference to thekeys K and K When either or both keys K and K are depressedsimultaneously with the key K, the effect of the pulsatory current willbe to cause variations in the strength of the current transmitted uponthe main line, without materially affecting its total strength. Theeffect, however, upon the receiving-instrument at station 11,corresponding to the key K will be the same as when that key alone isdepressed.

Referring now to the receiving apparatus at station II, threeinstruments, R R R, are provided, which instruments are adapted torespond, respectively, to the currents occaand K, whether those keys bedepressed one at a time or two or more simultaneously. To effect thisresult I provide the electro-magnet m of the receiving-instrument R witha yielding contact lever, r, which carries a stop against which the mainarmature-lever,r, plays in lieu of the usual fixed stop. Thiscontactlever r is normally held by a spring, t, against a fixed stop, 8,and the local circuit of a bat tery, p, which includes a sounder, S, is'made 5 will be sufficient to cause the armature-lever r to come incontact with the contact-lever 1*, but it will be insuiiicient toovercome the tension of the retraetile spring t. A circuit willtherefore be closed through the sounder S un- 'der the influence of sucha current. A current due to an electromotive force of twenty volts,however, will be sufficient to overcome the tension of the retractilesprings 23 and t and interrupt-the local circuit by breaking the.circuit betweenthe contactlever r and The sounder S of the receivingthestop 8.

instrument R will therefore respond to those currents only which aretransmitted while the key K is depressed. The receivinginstru Inent Rfor responding to the movements of the key K consists of anelectro-magnet, m provided with a polarized armature, r", adapted to bethrown, under the influence of cur rents of negative polarity and due toan electro-motive force of ten volts or more, against a contact-stop, 8thereby closing the circuit of a local battery, 1), and actuating thesounder S The receiving-instrument R adapted to respond to therhythmical vibrations produced by the transmitter K consists of anelectro magnet, an, provided with a reed armature, 9", tuned to the samepitch as the transmitting-reed, and capable, therefore, of respondingonly to electrical vibrations or undulations having the same frequencyor fundamental pitch as those occasioned by the transmitter K. A localbattery, includes in its circuit a suitable instrument, S, actuated byand in correspondence with the contacts of the reed g with thecontact-point s", occasioned by the movements of the armature r In thismanner I am enabled to transmit over one line, by means of threedifferent transmitting devices at station I, currents of differentcharacters which will be received and responded to by one, two, or threeinstruments at station II.

For the purpose of transmitting messages simultaneouslyin oppositedirections overthe same wire, the apparatus above described may becombined with any suitable system of duplexing of well-knownconstruction.

In Fig. 2 I have illustrated a method of applying my invention toquadruplex telegraphy, which consists in employing one solenoid only forcreating the magnetic field for the armatnre FA, and in organizing thetransmitting apparatus either for varying the strength of the currentwhich normally traverses the solenoid, or for reversing its polarity.The means which I employ for this purpose consist of twotransmitting-keys, K and K one of which, K", is a pole-changing keyadapted to reverse the poles of the battery 0, with reference to theirconnections with the terminals of the solenoid 0*, while the other key,K is arranged to throw in or out of circuit a portion of the mainbattery. For this purpose I prefer to construct the main battery 0 intwo sections, 0 and 0 the section 0 having preferably an electro-motiveforce of about five volts, while that of the section 0 is ten volts. Thekey K consists of an arm, k, constituting the key lever and extendingbetween two supplemental levers or arms, It and k into electricalcontact with either of which it may be brought.-

A resting contact-stop, s, is provided common to both supplementallevers 7c and 75-, and against which one or the other rests when not incontact with the key-lever k. The resting contact 5- is connected by awire, 11, with one pole-in thisinstance the negative of the batteryO-while the key-lever 7c is connected by the wires 5 and 6 with theopposite pole of the same battery. The supplemental levers k and k arerespectively connected with the terminals 9 and 10 of the solenoid c.

The.transmitting-key K consists of a lever, k connected by the wire 6with the positive pole of the battery-section 0 and provided with asupplemental lever, k", connected by a wire, 8, with the positive poleof the batterysection 0. The supplemental lever 75* normally rests upona contact-point, 0, through which the two battery-sections 0 and 0 arenormally connected. When the key-lever k is pressed upward against thelever the connection between the two battery-sections will be broken.

It will be understood from the foregoing that by operating the key K theelectro-motive force of the battery furnishing the current whichnormally traverses the solenoid a will be reduced from fifteen to fivevolts, and by means of the key K the polarity of the current traversingthe solenoid, whether it proceed from both battery-sections or thesection 0 alone, may be reversed. erated in the coils a of the armatureA and transmitted to line will vary accordingly. Thus normally a currentwill be transmitted upon the main line having a strength dependent uponthe revolution of the armature at a given rate within the magnetic fieldcreated by a positive current proceeding from a battery having anelectro-motive force of fifteen volts and traversing the solenoid c. Ifthe key K alone be depressed, the polarity of this current will bereversed,while its strength remains the same. If key K alone bedepressed, the current will be diminished in proportion to thediminution in the strength of the solenoid-current, and if both keys Kand K be simultaneously depressed the normal current upon the main linewill be diminished to the same extent as when the key K alone isdepressed, and its polarity at the same time reversed. The currents ofthe three different characters thus generated may be caused to actuateany suitable receiving-instruments at the distant station.

In the drawings I have shown two receivinginstruments, R" and R arrangedto respond to the movements of the keys K* and K, respectively. Theinstrument R" consists of an electro-magnet, m, included in the circuitof the main line and provided with a polarized armature, r, themagnetization of which is such as to cause it to respond to positivecurrents transmitted from the main line through the coil of its electromagnet by striking against the sounding-post q in opposition to theforce exerted by the retractile spring it, but remaining inactive underthe influence of a negative current.

The receiving-instrument R consists of an electro-magnet, m likewiseincluded in the circuit of the main line, but provided with a Thecurrents genneutral armature, 1-, carried upon an armature-lever, g henresting against its back contact-stop, 8 the armature-lever g closesthecircuit of a local battery, p and actuates a sounder, S in a mannerwell understood.

A retractile spring, 9, is adjusted to exert a sufficient tension uponthe armature-lever g to cause it to rest against its back contact-stopat other times than when it is attracted by a current of greaterstrength than that generated in thearmature A under the influence of anelectro-motive force of five volts. The spring i will, however, yield tothe magnetism produced by a current of greater strength, and of eitherpolarity, traversing the coils of its electro-magnet, and bring thearmature-lever Q5 against the front contact, thus breaking the localcircuit.

The operationwill be as follows: IVhenboth keys are open, a negativecurrent due to an electro-motive force of fifteen volts will traversetheline. The polarized armature T will be held against the restingcontact-stop 25, both by, virtue of the retractile spring and themagnetism induced in the cores of its electro-magnet. The neutralarmature r however, will be attracted with sufficient force to overcomethe tension of the spring t and its lever will rest against its frontcontact, the sounder S being therefore inactive. If the key K bedepressed, a positive current due to an electro-motive force of fifteenvolts will traverse the main line, and the polarized armaturer willrespond ac cordingly. The reversal of the polarity of the current willbe too rapid, however, to allow the armature r to fall away from itselectromagnet, and the sounder S will still remain inactive. If the keyK alone be depressed, a negative current due to an electro-motive forceof five volts will traverse the main line. This current will produce inthe electro-magnet m magnetism'of the polarity which tends to repel itsarmature o from the soundingpost Q4, and the receiving-instrument Itwill therefore remain inactive. The same current, however, will beinsufficient to maintain the armature r in its forward position inopposition to the force exerted by its retractile spring t and its leverwill therefore fall against the back contact, 8", and cause the sounderS to be actuated. WVhen both keys K and K are simultaneously depressed,a

negative current due to an electro-motive scribed with reference to Fig.2. The plan, however, consists in employing a battery of constantelectro-motive force, and throwing in or out of circuit a greater orless portion of the solenoid surrounding the armature,instead of varyingthe electro-motive force of the battery. I

1n the drawings I have represented the armature A as surrounded by onesolenoid, O,

composed of two sections, 0 and 0 The two sections are normallyconnected with each other by means of a'lever, is, resting upon acontact-stop, s A battery, 0, having an electro-motive force of, say,fifteen volts, is normally'so connected with the terminals of thesolenoid O that a positive current traverses the entire solenoid in thedirection indicated by the arrow. Two transmitting-keys, K and K, areprovided, the former of which is of the same general construction as thekey K described in connection with Fig. 2, and is arranged to reversethe poles of the battery 0 with reference to its connections with theterminals of the solenoid by connecting the positive pole of the batterythrough the wire 11 and key-lever 7a with the supplemental lever 2: orit, according as the key K is elevated or depressed, and thus by meansof one of the wires 12 or 14 with one or the other terminal of thesolenoid C Y The key K consists of a lever, k connecte by a wire, 13,with the conductor 2, leading to one terminal of the solenoid G. hen thekey K is depressed, it comes in contact with the lever It, raising itfrom the contact-stop s and closing the circuit of the battery 0 throughthe wire 11, key-lever k, and contact-spring k wires 12 and 13, key-lever If, supplemental lever k solenoid-section c, and wire 14 to thecontact-spring k and stop S", and by the wire 15 to the negative pole ofthe battery 0, thus cutting the solenoid-section 0 out of circuit. Thusthe key K serves to reverse the polarity of the battery 0, while the keyK determines whether the entire solenoid or only the section 0 beincluded in circuit. Supposing the solenoid-sections c and o be soconstituted that the induced current generated in the coils of thearmature A by'its revolution through the magnetic field produced by thecurrent from the battery 0 traversing the solenoid-section c has astrength one-thi rd as great as that generated when the currenttraverses both sections 0 and c then when both keys are in their normalposition the current transmitted to line may be considered as a positivecurrent due to an electromotive force of fifteen volts. When the key Kis depressed, it will be a negative current of the same strength." Whenthe key K alone is depressed, it will be a positive current of onethirdthe normal strength, and when both keys K and K are simultaneouslydepressed it will be a negative current of one-third the normalstrength. In this manner, by operating the keys K and K individually andin combination, currents of the same character maybe transmitted to themain line, as described with reference to Fig. 2, and these may beemployed for actuating any suit-able receiving-instruments at thedistant station, preferably, however, such as described in connectionwith Fig. 2.

It is obvious that any suitable and wellknown system for transmittingand receiving currents in opposite directions over the same line may becombined with the devices shown in Figs. 2 and 3, as well as with thatshown in Fig. 1.

I am aware that it is not new to employ induced currents for actuatingthe receiving-in struments of a telegraphic system, as it has beenproposed to locate a magneto-electric generator at the receiving-stationof such a system, and to include the coils of its fieldmagnets in thecircuit of the main line, the receiving-instruments in such case beingincluded in a local circuit with the armature of the generator. In suchan organization, however, the transmitting-instruments must be locatedin the circuit of the main line, and the incoming impulses are thuscompelled to pass through the same, whereas in my organization suchcurrents are provided with an earth-connection which is independent ofthe transmitting-instruments, and is, moreover, of practically constantresistance.

I claim as my invention- 1. The combination, substantially ashereinbefore set forth, with the armature of an electric generator andone or more solenoids for establishing a field of force for saidarmature, of one or more excitinggenerators, independent devices fortransmitting at will electric currents, impulses, or undulations fromsaid exciting generator or generators through the conductor orconductors constituting said solenoid or solenoids, a main line, andconnections, substantially such as described, for transmitting electriccurrents from the coils of said armature upon said main line.

2. The combination, substantially as hereinbefore set forth, with thearmature of an electric generator, of a main line, means for maintainingthe terminals oii said mainline in electric connection with the coils ofsaid armature, one or more solenoids for establishing a field of forcefor said armature, one or more local electric generators, and means fortransmitting at will determinate electric currents, impulses, orundulations through any or all of said solenoids.

3. The combination, substantially as hereinbefore set forth, with thearmature of an electric generator, its commutator and commutatorbrushes, and means, substantially such as described, for establishing orvarying the field of force of said armature, of an inde pendent mainline connected with the earth through said commutator andcon1mutatorwith the earth through said commutatorbrushes, and one ormore telegraphic receivbrushes, and receiving-instruments includeding-instruments included in said main line. in said main line.

4. The combination, substantially as here- In testimony whereof I havehereunto sub- 5 inbefore set forth, With the armature of an scribedmyname this24th day of August, A. D. I 5

electric generator, its commutator and com- 1882. mutator-brushes, andtransmitting devices for STEPHEN D. FIELD. controlling the field offorce created by electric WVitnesses: currents traversing the solenoidsof said gen- DANIEL W. EDGEOOMB,

IO erator, of an independent main line connected CHARLES A. TERRY.

